Effects of acute and chronic waterborne exposure to alkylphenols on early life stages of Cichlasoma dimerus (Teleostei, Perciformes)

F. MEIJIDE; Y. PIAZZA; F. LO NOSTRO; G. GUERRERO

Mar del Plata

Congreso; II Congreso SETAC Argentina; 2008

SETAC Argentina

Endocrine disrupting compounds (EDCs) are often detected in the aquatic environment and can negatively affect the health of wildlife populations. However, little is known about the sensitivity of native fishes to EDCs. Alkylphenols, such as 4-tert-octylphenol (OP) and 4-nonylphenol (NP), are biodegradation products of non-ionic surfactants used in domestic and industrial activities and exhibit estrogenic effects. In teleost fishes, the hormonal environment present during a critical period of larval development may have influence on gonadal sex differentiation, and then this process may be affected by the exposure to EDCs. In this study, we assessed the lethal acute toxicity of OP and NP on larval stages of the teleost fish Cichlasoma dimerus and evaluated the effect of chronic exposure to environmentally relevant concentrations of this xenoestrogens on gonadal development and sex differentiation. Treatments with the natural estrogen 17b-estradiol (E2) were performed as positive controls. LC50-96 h for three larval stages were determined by means of standard acute toxicity tests using a semistatic method. NP was slightly more toxic than OP to all the larval stages assessed. In addition, the lethal acute toxicity of these compounds decreased as larval development progressed. In subsequent experiments, animals were exposed before and during the period of gonadal sex differentiation to 1, 10 and 100 mg/l OP and E2 via immersion in a static-renewal system. Larval mortality was recorded for each treatment. At the end of the experiments, the sex was determined by gross gonadal inspection and later confirmed by histology. The exposure to E2 had a pronounced feminizing effect, directing the process of sex differentiation towards the females. The exposure to environmentally relevant concentrations of OP had a weak estrogenic effect on sex differentiation, as evidenced by the appearance of a low number of males exhibiting gonadal intersex (testis-ova).